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Altered EEG Functional Connectivity and Impaired Speech Control in Post-Stroke Aphasia
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Poster D55 in Poster Session D, Wednesday, October 25, 4:45 - 6:30 pm CEST, Espace Vieux-Port
Kimaya Sarmukadam1, Roozbeh Behroozmand1; 1University of South Carolina
Introduction: Synchronization of oscillatory brain activity has been proposed to reflect the underlying neurocomputational processes that are critical for speech production and sensorimotor control. While there is evidence for altered neural or brain connectivity in sensorimotor networks during speech processing and production in individuals with left-hemisphere stroke, the impact of network-level deficits associated with disrupted speech auditory feedback control in post-stroke aphasia has yet to be widely explored. Methods: Electroencephalographic signals were recorded from 40 post-stroke aphasia (17 female; mean age: 61.04 years) and 39 neurologically intact control (29 female; mean age: 61.18 years) participants during speech vowel production and listening tasks under pitch-shifted altered auditory feedback (AAF; delivered at ±100 cents magnitudes) conditions. Using weighted phase-lag index (wPLI), we calculated broadband (1-70 Hz) functional connectivity between electrode pairs covering the frontal, pre- and post-central, and parietal regions. We also investigated associations between connectivity and motor speech compensatory behavior and left-hemisphere lesion profiles. Results: wPLI analysis revealed reduced fronto-central delta- (1-4 Hz) and theta- (4-7 Hz) band and centro-parietal low-beta (13-20 Hz) band connectivity in electrodes covering the left-hemisphere and diminished speech AAF compensation responses in post-stroke aphasia as compared with controls. Lesion mapping analysis demonstrated that stroke-induced damage to multi-modal brain networks within the inferior frontal gyrus, Rolandic operculum, inferior parietal lobule, angular gyrus, and supramarginal gyrus predicted reduced functional neural connectivity within the delta and low-beta bands during both speaking and listening tasks in aphasia. Conclusion: Findings from the current study provide novel insights into network-wide disrupted EEG functional connectivity in participants with post-stroke aphasia associated with atypical modulation of speech compensatory responses under AAF conditions. In addition, our findings also suggest that stroke-induced damage in speech sensorimotor networks predict atypical speech compensation and disrupted low-beta band connectivity, potentially indicative of functional reorganization. These findings motivate future research to further examine the complex interplays between brain connectivity and sensorimotor deficits, thereby, introducing more avenues for interventions of speech disorders in post-stroke aphasia and other neurological conditions.
Topic Areas: Speech Motor Control, Multisensory or Sensorimotor Integration